Substrate

ABSTRACT

A substrate and a method for producing the same are disclosed herein. In some embodiments, a substrate includes a base layer, a black layer formed on the base layer, and column spacers formed on the black layer, wherein a loss rate of spacers measured by a peel test is 15% or less. The substrate can have excellent adhesiveness of the spacer to the base layer or the black layer and ensuring appropriate darkening properties. The method can effectively produce such a substrate without adverse effects such as occurrence of foreign materials without separate treatment such as heat treatment.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application is a divisional of U.S. application Ser. No.16/780,243, filed on Feb. 3, 2020 which is a continuation ofInternational Application No. PCT/KR2018/009329, filed on Aug. 14, 2018,which claims priority from Korean Patent Application No.10-2017-0104654, filed on Aug. 18, 2017, the disclosures of which areincorporated by reference herein.

TECHNICAL FIELD

The present application relates to a substrate and a method forproducing the same.

BACKGROUND ART

An optical device capable of adjusting light transmittance or colors orreflectance by disposing a light modulating material comprising a liquidcrystal compound between substrates disposed opposite to each other isknown.

For example, Patent Document 1 discloses a so-called GH cell (guest hostcell) applying a mixture of a liquid crystal host and a dichroic dyeguest.

In such a device, so-called spacers are located between the substratesto maintain the spacing between the substrates.

In some cases, the spacers may need to be darkened depending on thestate in which the optical device is implemented. As a method fordarkening the spacer, there is a method that as a black layer is formedon a base layer and a spacer is formed thereon, the spacer looks blackwhen observed on the base layer side or the top.

Prior Art Documents Patent Documents

-   Patent Document 1: European Patent Publication No. 0022311

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1, 2, 4 to 7 are diagrams showing structures of exemplarysubstrates in accordance with the present disclosure.

FIG. 3 is an exemplary diagram showing the form of forming a spacer.

FIGS. 8 to 11 are schematic diagrams of exemplary forms of spacers inaccordance with the present disclosure.

FIGS. 12 to 17 are diagrams for explaining exemplary forms of spacers inaccordance with the present disclosure.

FIG. 18 is a diagram for explaining a method of implementing a degree ofirregularity in accordance with the present disclosure.

FIGS. 19 and 21 are diagrams schematically showing the process ofproducing a substrate in accordance with the present disclosure.

FIG. 20 is an example of a mask shape applied in the process ofproducing a substrate in accordance with the present disclosure.

FIGS. 22A-B illustrate top down and side views, respectively, ofscanning electron microscopy (SEM) images showing the shape of thespacer produced in Example 1 and its arrangement on the substrate inaccordance with the present disclosure.

FIG. 23 is a view showing the result of evaluating adhesiveness of thespacers produced in Example 1 to the black layer in accordance with thepresent disclosure.

FIG. 24 is a view showing the result of evaluating whether or notforeign materials occur with respect to the spacers produced in Example1 in accordance with the present disclosure.

FIG. 25 is a view showing the result of evaluating whether or notforeign materials occur with respect to the spacer produced in Example 2in accordance with the present disclosure.

FIG. 26 is a view showing the result of evaluating adhesiveness of thespacers produced in Example 2 to the black layer in accordance with thepresent disclosure.

FIG. 27 is an OM image showing the result of forming a rubbing alignmentfilm on the spacers produced in Example 2 in accordance with the presentdisclosure.

FIGS. 28 and 29 show the results of evaluating whether or notadhesiveness is present for the spacers formed in Comparative Examples 1and 2, respectively.

FIGS. 30 and 31 show the results of evaluating whether or not foreignmaterials occur for the spacers formed in Comparative Examples 3 and 4,respectively.

DISCLOSURE Technical Problem

The present application provides a substrate and a method for producingthe same. An object of the present application is to provide a substrateensuring good adhesion between a spacer and a base layer and/or a spacerand a black layer in a state where appropriate darkening is ensured, andanother object is to provide a method capable of simply and effectivelyproducing such a substrate without adverse effects such as occurrence offoreign materials.

Technical Solution

Among physical properties mentioned in this specification, when themeasured temperature affects the results, the relevant physicalproperties are physical properties measured at room temperature, unlessotherwise specified. The term room temperature is a natural temperaturewithout being heated or cooled, which may be, for example, anytemperature in a range of 10° C. to 30° C., or about 23° C. or about 25°C. or so. In addition, unless otherwise specified herein, the unit oftemperature is ° C.

Among physical properties mentioned in this specification, when themeasured pressure affects the results, the relevant physical propertiesare physical properties measured at room pressure, unless otherwisespecified. The term normal pressure is a natural pressure without beingpressurized or depressurized, where usually about 1 atm is referred toas the normal pressure.

The present application relates to a substrate and a method forproducing the same, and in one example, the substrate may have astructure that comprises a base layer and a spacer present on the baselayer, and also comprises a black layer between the spacer layer and thebase layer. FIGS. 1 and 2 are diagrams showing, as an exemplarysubstrate of the present application, the case where the spacer (20) ispresent on a base layer (10).

In the substrate of the present application, the spacer exhibitsexcellent adhesion to the base layer or elements of the base layer (forexample, an electrode layer or the black layer) that the spacercontacts.

For example, the loss rate of the spacers measured by performing a peeltest on the surface of the base layer on which the spacers are formedmay be about 15% or less or so. The peel test is performed by attachinga pressure-sensitive adhesive tape having peel force in a level of about3.72N/10 mm to 4.16N/10 mm on the surface of the base layer on which thespacers are formed, and then peeling it off. As the pressure-sensitiveadhesive tape, a tape known as a Nichiban Tape CT-24 can be used. TheNichiban tape has the peel force in a level of about 3.72N/10 mm to4.16N/10 mm as measured at a peel angle of 180 degrees in accordancewith JIS Z 1522 standard. The peel test may be performed by attachingthe Nichiban tape CT-24 to the surface of the base layer, on which thespacers are formed, with a rectangular attachment area of 24 mm in widthand 40 mm in length and then peeling the Nichiban tape CT-24 in thelongitudinal direction at a peel rate of about 30 mm/s and a peel angleof about 180 degrees. The loss rate of the spacers measured byperforming the peel test may be 15% or less, 13% or less, 11% or less,9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less,3% or less, 2% or less, 1% or less, or 0.5% or less. Here, the loss ratemay be a percentage of the number of spacers that have been lost afterpeeling the pressure-sensitive adhesive tape off relative to the numberof all the spacers existing within the attachment area. Depending on theapplied use, usually 10,000 to 40,000 spacers may be present in theabove attachment area, where the ratio of the spacers to be lost amongthese spacers may be maintained in the above range.

In the case of the substrate structure of the present application, it isnot easy to control the curing rate of the spacer material due to thepresence of the black layer or the like, and thus it is very difficultto form the spacer with excellent sticking force as above. However,according to the production method of the present application to bedescribed below, excellent adhesiveness as described above can beensured in a state where darkening is effectively performed.

In the case where the spacer exhibits such adhesiveness, even if analignment film is formed on the surface and alignment treatment such asrubbing proceeds, the spacer may be stably maintained, so that it ispossible to finally manufacture a product having excellent performance.In addition, the substrate on which the spacer is formed can bemaintained in a state where a protective pressure-sensitive adhesivefilm is attached to the surface on which the spacer is formed until itis applied to an actual product, where in such a structure, the patterncan be stably maintained without being lost, even if thepressure-sensitive adhesive film is peeled off.

As the base layer, any base layer used in a substrate in a configurationof a known optical device such as an LCD (liquid crystal display) can beapplied without particular limitation. For example, the base layer maybe an inorganic base layer or an organic base layer. As the inorganicbase layer, a glass base layer or the like can be exemplified, and asthe organic base layer, various plastic films or the like can beexemplified. The plastic film can be exemplified by a TAC (triacetylcellulose) film; a COP (cycloolefin copolymer) film such as a norbornenederivative; an acrylic film such as PMMA (poly(methyl methacrylate); aPC (polycarbonate) film; a polyolefin film such as PE (polyethylene) orPP (polypropylene); a PVA (polyvinyl alcohol) film; a DAC (diacetylcellulose) film; a Pac (polyacrylate) film; a PES (polyether sulfone)film; a PEEK (polyetheretherketone) film; a PPS (polyphenylsulfone)film, a PEI (polyetherimide) film; a PEN (polyethylenemaphthatate) film;a PET (polyethyleneterephtalate) film; a PI (polyimide) film; a PSF(polysulfone) film or a PAR (polyarylate) film, and the like, but is notlimited thereto.

In one example, the base layer may be a so-called flexible base layer.In the present application, a black layer to be described below can alsobe effectively formed on the flexible base layer without defects such ascracks, and durability of the black layer can be secured even when thebase layer is bending according to applications or the like. Thespecific kind of the flexible base layer is not particularly limited,and among the above-described base layers, a plastic film or a very thininorganic base material such as thin glass can be mainly used as theflexible base layer.

In the substrate of the present application, the thickness of the baselayer is also not particularly limited, where an appropriate range maybe selected depending on applications.

A spacer is present on the base layer. The spacer may be fixed to thebase layer. In this case, the spacer may be fixed directly in contactwith the base layer, or if there are other layers between the base layerand the spacer, it may be fixed on the relevant other layer. The kind ofthe other layer includes a known layer necessary for driving the opticaldevice, and for example, an electrode layer or a black layer, and thelike, which is described below, can be exemplified.

In one example of the substrate of the present application, the spacermay be a transparent column spacer, and a black layer may be formed onthe bottom of the transparent column spacer.

Here, the fact that the spacer is transparent means a case where thetransmittance for light having at least one of wavelength regions or theentire wavelength region in the visible light region is 50% or more, 55%or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% ormore, 85% or more, or 90% or more, and in this case, the upper limit ofthe transmittance is not particularly limited. The transparent columnspacer as above can be formed by a method to be described below using atransparent resin. Typically, the visible light region is approximately380 nm to 720 nm, and in one example, the transmittance can be measuredat a wavelength of approximately 550 nm.

In the present application, the shape of the column spacer is notparticularly limited, and for example, a cylindrical shape, a polygonalcolumn shape such as a triangular, quadrangular, pentagonal or hexagonalcolumn shape, a hemispherical shape, a mesh shape or other shapes can beall applied. FIG. 1 is a cross-sectional diagram to which a quadranglecolumnar spacer (20) is applied, and FIG. 2 is a cross-sectional diagramto which a hemispherical spacer (20) is applied.

In the present application, a black layer is present on the bottom ofthe transparent column spacer, i.e., between the transparent columnspacer and the base layer.

In this specification, the term top means the direction from the baselayer toward the spacer formed on the base layer, and the bottom meansthe opposite direction of the top. Here, the black layer may also mean alayer having an optical density of about 1 to 6 or so. The black layermay also exhibit the optical density when observed in any one directionof the top and the bottom of the substrate, and in some cases, it mayexhibit the optical density when observed in both of the top and bottomsides. The optical density can be obtained by measuring thetransmittance (unit: %) of the black layer and then substituting it intoan equation of optical density (optical density=−log₁₀ (T), where T isthe transmittance). In another example, the optical density may be about1.5 or more, 2 or more, 2.5 or more, 3 or more, 3.5 or more, 4 or moreor 4.5 or more or so, or may be about 5.5 or less or 5 or less or so.

FIG. 3 is a schematic diagram showing a case where a black layer isformed on the upper or lower part of a hemispherical, cylindrical,rectangular columnar or mesh-shaped spacer.

In an optical device capable of adjusting light transmittance, colorsand/or reflectance, the region where the spacer exists becomes anoptically inactive region. Therefore, in some cases, it is necessary toblack the region where the spacer exists. To this end, for example, amethod of blacking the spacer itself, such as a method of manufacturinga column spacer using a black resin, may be considered, but in such acase, since the black resin itself absorbs light, so that a curingprocess is not easy, it is not easy to manufacture a high step spacer.However, the introduction of such a structure can form a substrate whichprevents degradation of optical characteristics due to inactive regionsupon driving an optical device, while being formed in high steps. Inaddition, when the structure is formed by a method to be describedbelow, it is also possible to manufacture the substrate having excellentadhesiveness as described above.

For example, the spacer may have a height in a range of 1 μm to 50 μm.In another example, the height may be 3 μm or more, 5 μm or more, 7 μmor more, 9 μm or more, 11 μm or more, 13 μm or more, 15 μm or more, 17μm or more, 19 μm or more, 21 μm or more, 23 μm or more, 25 μm or more,or 27 μm or more, and may also be 48 μm or less, 46 μm or less, 44 μm orless, 42 μm or less, 40 μm or less, 38 μm or less, 36 μm or less, 34 μmor less, 32 μm or less, 30 μm or less, 28 μm or less, or 26 μm or less.

The black layer may be formed using various materials capable ofrealizing black. For example, the black layer may be a metal layer, ametal oxide layer, a metal nitride layer or a metal oxynitride layer, ormay be a layer containing a pigment or a dye.

The specific material of the black layer is not particularly limited,and for example, a metal such as Ni, V, W, Ta, Mo, Nb, Ti, Fe, Cr, Co,Al or Cu, an alloy metal containing two or more of the metals, an oxide,a nitride or an oxynitride of the metal, and the like can be used, andvarious pigments or dyes capable of realizing black can also be used.

Depending on the purpose, the black layer may have a single-layerstructure or a multilayer structure. In one example, the black layer mayhave a multilayer structure in order to achieve the desired darkeningwhile ensuring process efficiency. For example, the black layer may havea multilayer structure of a two-layer structure comprising a first layerwhich is a metal layer and a second layer which is a metal oxide layer,a metal nitride layer or a metal oxynitride layer, or a three-layerstructure in which the second layer is formed on both sides of the firstlayer. In one example, the second layer may be a metal oxynitride layer.FIGS. 4 and 5 are examples of a substrate on which a black layer havinga three-layer structure, wherein the first layer (301) and the secondlayer (302) are formed thereon as above, is formed. In such a multilayerstructure, the inherent refractive indexes, transmission characteristicsand/or reflection characteristics of the first layer and the secondlayer may be correlated with each other to attain an appropriatedarkening, and particularly, in the case of the above-mentionedmultilayer structure of three layers or more, the appropriate darkeningmay be achieved on both sides of the black layer. The specific kind ofthe metal, the metal oxide, the metal nitride and/or the metaloxynitride used in the first layer and the second layer is notparticularly limited, and for example, a suitable kind among theabove-mentioned materials can be selected. In one example, the secondlayer may have an oxide, nitride or oxynitride containing the same metalas applied in the first layer.

The spacer and the black layer as above may be overlapped with eachother when viewed from the top or bottom.

The black layer may have an area equal to or smaller than that of thebottom of the spacer. That is, for example, the black layer may existonly substantially within the area where the spacer is present. Forexample, the ratio (T/B) of the area (B) of the black layer and the area(T) of the bottom of the spacer may be in a range of 0.5 to 1.5. Inanother example, the ratio (T/B) may be about 0.55 or more, about 0.6 ormore, about 0.65 or more, about 0.7 or more, about 0.75 or more, about0.8 or more, about 0.85 or more, about 0.9 or more, or about 0.95 ormore. Also, in another example, the ratio (T/B) may be about 1.45 orless, about 1.4 or less, about 1.35 or less, about 1.3 or less, about1.25 or less, about 1.2 or less, about 1.15 or less, about 1.1 or less,or about 1.05 or less. In this arrangement, it is possible to suitablyprevent light leakage or the like from being caused upon driving theoptical device, while ensuring adequate adhesion of the spacer to thesubstrate.

Such a black layer may have an appropriate thickness in consideration ofthe desired step and darkening, and the like. For example, the thicknessof the black layer may be in a range of 30 nm to 5000 nm. The thicknessof each layer in the case where the black layer is formed in amultilayer structure can also be selected in consideration of thedesired step and/or darkening, and the like. For example, in theabove-mentioned multilayer structure, each of the first layer and thesecond layer may have a thickness in a range of 30 nm to 200 nm.

In one example, the black layer may be formed based on a material havinga physical ductility value of 0.6 or more. In this specification, theterm physical ductility value is a value known in the industry permaterial, which is a value obtained through the following equations Aand B based on the Poisson ratio (v) of the material. The physicalductility value has a value in a range of 0 to 1, which means that asthe value is closer to 1, the material has more ductile characteristics.

$\begin{matrix}{\kappa = \frac{1 - {2v}}{1 + v}} & \left\lbrack {{Equation}A} \right\rbrack\end{matrix}$

In Equation A, v is the Poisson's ratio of the material.D=3x ²−2x ³  [Equation B]

In Equation B, D is the physical ductility value, x is the valueobtained by Equationx=(1−κ)², and κ is the value obtained in Equation A.

The black layer may comprise a material having the physical ductilityvalue of 0.55 or more, where the material may be, for example, a metal.By applying such a material, it is possible to solve a problem thatcracks occur in a process of forming a black layer or in the case wherethe substrate is bent depending on applications, and the like, or otherdefects occur. In another example, the physical ductility value may alsobe about 1 or less, about 0.95 or less, about 0.9 or less, about 0.85 orless, about 0.8 or less, about 0.75 or less, about 0.7 or less, or about0.65 or less or so, and may also be about 0.6 or more. Such a materialcan be exemplified by, for example, gold (Au, physical ductility: about0.93), lead (Pb, physical ductility: about 0.93), niobium (Nb, physicalductility: about 0.82), palladium (Pd, physical ductility: about 0.80),platinum (Pt, physical ductility: about 0.76), silver (Ag, physicalductility: about 0.73), vanadium (V, physical ductility: about 0.73),tin (Sn, physical ductility: about 0.69), aluminum (Al, physicalductility: about 0.65) or copper (Cu, physical ductility: about 0.62),and the like, but is not limited thereto.

The contents related to the black layer already described herein can beequally applied using a material having the physical ductility value of0.6 or more.

For example, the metal layer, the metal oxide layer, the metal nitridelayer, and/or the metal oxynitride layer can be formed using a metalhaving the physical ductility value of 0.6 or more, and the contents ofwhether a single layer or multilayers, thickness, other forms, and thelike can also be applied equally.

The shape of the spacer formed together with the black layer is notparticularly limited, as described above.

The spacer includes a curved portion. In one example, the spacer may bea hemispherical spacer where the curved portion is a hemisphericalportion that is formed at least at the top end of the spacer. Byapplying the spacer having such a curved portion, even when orientationtreatment such as rubbing orientation or photo-orientation is performedafter an alignment film is formed on the base layer on which the spaceris formed, the uniform orientation treatment can be performed even inthe region where the spacer exists without influence of the step by thespacer.

In the present application, the term curved portion may mean a part ofthe spacer including a curved shape in which the trajectory of the crosssection has a predetermined curvature. In addition, the trajectory ofthe cross section of the hcurved portion may include a curved part wherethe center of curvature is present inside the cross-sectionaltrajectory.

In one example, the curved portion may have a maximum curvature of thecross-sectional trajectory of 2,000 mm⁻¹ or less. As is known, thecurvature is a numerical value representing a degree of curvature of aline, which is defined as an inverse number of a radius of curvaturewhich is a radius of a contact circle at a predetermined point of therelevant curve. In the case of a straight line, the curvature is 0, andthe larger the curvature, the more curved the curve exists.

By controlling the degree of bending of the curved portion so that themaximum curvature of the cross-sectional trajectory of the hemisphericalportion is 2,000 mm⁻¹ or less, the uniform orientation treatment can beperformed even when the orientation treatment of the alignment film isperformed at the top of the curved portion. Here, the cross section forconfirming the cross-sectional trajectory of the hemispherical portionmay be any normal plane for the base layer. In addition, the maximumcurvature may mean the largest curvature among the curvatures for allthe contact circles that can be obtained on the cross-sectionaltrajectory of the curved portion. In other words, the cross-sectionaltrajectory of the curved portion may not include the bent portion suchan extent that the curvature exceeds 2,000 mm⁻¹.

In another example, the maximum curvature may be 1,800 mm⁻¹ or less,1,600 mm⁻¹ or less, 1,400 mm⁻¹ or less, 1,200 mm⁻¹ or less, 1,000 mm⁻¹or less, 900 mm⁻¹ or less, 950 mm⁻¹ or less, 800 mm⁻¹ or less, 750 mm⁻¹or less, 700 mm⁻¹ or less, 650 mm⁻¹ or less, 600 mm⁻¹ or less, 550 mm⁻¹or less, 500 mm⁻¹ or less, 450 mm⁻¹ or less, 400 mm⁻¹ or less, 350 mm⁻¹or less, 300 mm⁻¹ or less, 250 mm⁻¹ or less, 200 mm⁻¹ or less, or 150mm⁻¹ or less or so. In another example, the maximum curvature may be 5mm⁻¹ or more, 10 mm⁻¹ or more, 15 mm⁻¹ or more, 20 mm⁻¹ or more, 25 mm⁻¹or more, 30 mm⁻¹ or more, 40 mm⁻¹ or more, 45 mm⁻¹ or more, or 50 mm⁻¹or more.

The cross-sectional trajectory of the curved portion may or may notinclude a portion having curvature of 0, that is, a linear portion.

For example, FIG. 8 is an example of a cross-sectional trajectory of acurved portion (e.g., a hemispherical portion) that does not include aportion having curvature of 0, and FIG. 9 is an example of across-sectional trajectory of a curved portion including a portionhaving curvature of 0.

The spacer may comprise the curved portion as above at least at the topend of the spacer. The spacer may be formed in various shapes as long asit comprises the hemispherical portion. For example, the spacer may be ashape in which the curved portion is directly formed on the surface ofthe base layer (100), as shown in FIG. 8 or 9 , or may be a columnarspacer including the curved portion at the top end, as shown in FIG. 10or 11 .

In the curved portion of the spacer, the cross-sectional trajectory maynot include a portion having curvature of 0, as shown in FIG. 8 or 10 ,or the cross-sectional trajectory may also include a portion (a flatsurface at the top end) having curvature of 0, as shown in FIG. 9 or 11. Hereinafter, for convenience, the curved portion of the same shape asthat of a hemisphere in FIG. 8 or 10 may be referred to as ahemispherical portion, and the curved portion having a shape in which aflat surface is formed on the top end of the spacer in FIG. 9 or 11 maybe referred to as a curved portion including a flat portion.

In FIGS. 8 to 11 , H2 is the height of the curved portion, R is theradius of curvature of the curved portion, W1 is the length (width) ofthe flat surface of the flat portion, W2 is the width of the spacer, H1is the value obtained by subtracting the height (H2) of the curvedportion from the total height of the spacer.

The curved portion may be a complete hemispherical shape or may be onehaving an approximately hemispherical shape. The complete hemisphericalshape may be a hemispherical shape satisfying Relational Expression 1 tobe described below, and the approximate hemispherical shape may be ahemispherical shape satisfying any one of Relational Expressions 2 to 4below.

The curved portion may have a shape in which the cross-sectional shapesatisfies any one of Relational Expressions 1 to 4 below.a=b=R  [Relational Expression 1]a≠b=R or b≠a=R  [Relational Expression 2]a=b<R  [Relational Expression 3]a≠b<R  [Relational Expression 4]

In Relational Expressions 1 to 4, a is the horizontal length of thecurved portion section measured at the center of the virtual contactcircle of the curved portion section, b is the vertical length of thecurved portion section measured at the center of the virtual contactcircle of the curved portion section, and R is the curvature radius ofthe virtual contact circle of the curved portion section.

The curvature radius in Relational Expressions 1 to 4 corresponds to thelength indicated by R in FIGS. 8 to 11 .

In Relational Expressions 1 to 4, the virtual contact circle may mean acontact circle having the largest curvature radius among a plurality ofvirtual contact circles in contact with the curved line forming thecurved portion.

If the curved portion is the complete hemispherical portion as shown inFIGS. 8 and 10 , the cross section of the curved portion as a whole is acurved line, and thus a contact circle having the largest curvatureradius among a plurality of virtual contact circles in contact with anypoint of the relevant curved line may be a contact circle as referred toin Relational Expressions 1 to 4. In addition, if the curved portionincludes a flat portion as shown in FIGS. 9 and 11 , a contact circlehaving the largest curvature radius among a plurality of virtual contactcircles in contact with any point of both side curved lines excludingthe flat line on the top in the curved portion section becomes a virtualcontact circle as referred to in Relational Expressions 1 to 4.

In Relational Expressions 1 to 4, the horizontal length is a lengthmeasured in a direction horizontal to the base layer surface (ReferenceNumeral 100 in FIGS. 8 to 11 ) at the center point of the virtualcontact circle, and the vertical length is a length measured in adirection vertical to the base layer surface (Reference Numeral 100 inFIGS. 8 to 11 ).

In Relational Expressions 1 to 4, a is the length from the center of thevirtual contact circle of the curved portion section to the point wherethe hemispherical portion is terminated as measured while proceeding inthe horizontal direction. This horizontal length may have two lengths ofa length from the center of the virtual contact circle as measured whileproceeding in the rightward direction and a length measured whileproceeding in the leftward direction, where a applied in RelationalExpressions 1 to 4 means a short length of the two lengths. In the caseof the curved portion having a shape of FIGS. 8 and 10 , the horizontallength (a) is a value corresponding to ½ of the width (W2) of thespacer. Also, in the case of FIGS. 9 and 11 , the value (2 a+W1)obtained by adding the length (width) (W1) of the flat portion to twicethe horizontal length (a) may correspond to the width (W2) of thespacer.

In Relational Expressions 1 to 4, b is the length from the center of thevirtual contact circle of the curved portion section to the point wherethe curved portion first meets while proceeding in the verticaldirection. Usually, this vertical length (b) may be approximately thesame as the height of the curved portion, for example, the lengthindicated by Symbol H2 in FIGS. 8 to 11 .

FIG. 12 is a cross-sectional curve shape of the curved portionsatisfying Relational Expression 1 above, which shows a case where thecurved line of the curved portion has a complete circle curve, that is,a curve coinciding with the virtual contact circle.

Also, FIGS. 13 to 17 show approximate curve shapes of the curved portionsatisfying any one of Relational Expressions 2 to 4.

A tapered portion, in which the cross-sectional trajectory is a curvedshape that the curvature center is formed outside the cross section, maybe formed at the bottom end of the spacer, for example, the bottomcontacting the base layer side. With this form, an excellent effectaccording to the specific shape of the spacer of the presentapplication, for example, achievement of the uniform orientationtreatment or the like can be further improved.

The dimension of the spacer having the same shape as above is notparticularly limited, which can be appropriately selected inconsideration of, for example, a cell gap of the desired optical deviceor an aperture ratio, and the like.

For example, the height of the curved portion (H2 in FIGS. 8 to 11 ) maybe in a range of 1 μm to 20 μm. In another example, the height may be 2μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, 7 μmor more, 8 μm or more, 9 μm or more, 10 μm or more, or 11 μm or more. Inanother example, the height may also be 19 μm or less, 18 μm or less, 17μm or less, 16 μm or less, 15 μm or less, 14 μm or less, 13 μm or less,12 μm or less, or 11 μm or less.

In addition, the width of the curved portion (W2 in FIGS. 8 to 11 ) maybe in a range of 2 μm to 40 μm. In another example, the width may be 4μm or more, 6 μm or more, 8 μm or more, 10 μm or more, 12 μm or more, 14μm or more, 16 μm or more, 18 μm or more, 20 μm or more, or 22 μm ormore. In another example, the width may be 38 μm or less, 36 μm or less,34 μm or less, 32 μm or less, 30 μm or less, 28 μm or less, 26 μm orless, 24 μm or less, or 22 μm or less.

When the spacer has the shape as shown in FIG. 8 or 9 , the height ofthe spacer may be the same as the height of the curved portion, and whenthe spacer has the shape as shown in FIGS. 10 and 11 , it may be a valueobtained by adding the height (H1) of a columnar portion to the heightof the curved portion. In one example, the height may be in a range of 1μm to 50 μm.

In another example, the height may be 3 μm or more, 5 μm or more, 7 μmor more, 9 μm or more, 11 μm or more, 13 μm or more, 15 μm or more, 17μm or more, 19 μm or more, 21 μm or more, 23 μm or more, 25 μm or more,or 27 μm or more. In another example, the height may be 48 μm or less,46 μm or less, 44 μm or less, 42 μm or less, 40 μm or less, 38 μm orless, 36 μm or less, 34 μm or less, 32 μm or less, 30 μm or less, 28 μmor less, or 26 μm or less.

By controlling the dimension of the spacer including or not including acolumn portion as above, the uniform orientation treatment can beperformed even with respect to the alignment film formed on the top ofthe spacer and the uniform cell gap can be maintained, and thus when thesubstrate has been applied to production of an optical device, theperformance of the relevant device can be excellently maintained.

The spacer can be formed using, for example, a transparent resin, asdescribed above. In one example, the spacer may be formed by comprisinga transparent ultraviolet curable resin. For example, it may be formedby curing the ultraviolet curable compound in a state where the shape ofthe ultraviolet curable compound is maintained in a state capable offorming a desired shape by an imprinting method to be described below,where the ultraviolet curable resin, which is a cured product of theultraviolet curable compound, can form the spacer. The specific kind ofultraviolet curable compound that can be used for forming the spacer isnot particularly limited, and for example, an acrylate-based polymermaterial or an epoxy-based polymer, and the like may be used, withoutbeing limited thereto.

The substrate of the present application may comprise, in addition tothe base layer and the spacers, other elements required for driving theoptical device. These elements are variously known, and typically, thereis an electrode layer or the like. FIG. 6 is an example of a structurein which an electrode layer (40) is formed between the black layer (30)and the base layer (10) in the substrate of the structure of FIG. 1 ,and FIG. 7 is an example of a structure in which an electrode layer (40)is formed between the black layer (30) and the base layer (10) in thesubstrate of the structure of FIG. 2 .

As in the drawing, the substrate may further comprise an electrode layerbetween the base layer and the spacers. As the electrode layer, a knownmaterial can be applied. For example, the electrode layer may comprise ametal alloy, an electrically conductive compound or a mixture of two ormore thereof. Such a material can be exemplified by a metal such asgold, CuI, an oxide material such as ITO (indium tin oxide), IZO (indiumzinc oxide), ZTO (zinc tin oxide), zinc oxide doped with aluminum orindium, magnesium indium oxide, nickel tungsten oxide, ZnO, SnO₂ orIn₂O₃, a metal nitride such as gallium nitride, a metal selenide such aszinc selenide, a metal sulfide such as zinc sulfide, or the like. Atransparent positive hole injecting electrode layer can also be formedby using a laminate of a metal thin film of Au, Ag or Cu, and the like,and a transparent material having high refractive index such as ZnS,TiO₂ or ITO.

The electrode layer may be formed by any means such as vapor deposition,sputtering, chemical vapor deposition or electrochemical means.Patterning of the electrode layer is also possible in a known mannerwithout any particular limitation, and the electrode layer may bepatterned, for example, through known photolithography or a processusing a shadow mask or the like.

The substrate of the present application may further comprise analignment film present on the base layer and the spacer.

Thus, another exemplary substrate of the present application maycomprise a base layer; a spacer present on the base layer; and analignment film formed on the base layer and the spacer.

Here, the details of the base layer and the spacer are as describedabove. In addition, the kind of the alignment film formed on the baselayer and the spacers is not particularly limited, where a knownalignment film, for example, a known rubbing alignment film or aphoto-alignment film can be applied. A method of forming the alignmentfilm on the base layer and the spacers and performing orientationtreatment thereon is also in accordance with a known method.

The base layer may comprise a plurality of spacers by comprising,including the spacer as mentioned above, the same or different spacers.Such a plurality of spacers may be disposed on the base layer whilehaving predetermined regularity and irregularity simultaneously.Specifically, at least a part of the plurality of spacers on the baselayer may be in an irregular arrangement in terms of being arranged soas to have pitches different from each other, but may be regular interms of being arranged with substantially the same density betweenregions determined according to a predetermined rule.

That is, in one example, at least a part of the spacers disposed on thebase layer may be disposed so as to have pitches different from eachother.

Here, when a part of the plurality of spacers have been selected so asto form a closed figure in a state where other spacers are not presenttherein, the term pitch can be defined as a length of a side of theclosed figure. In addition, unless otherwise specified, the unit of thepitch is μm.

The closed figure thus formed may be a triangle, a quadrangle or ahexagon. That is, when three spacers among the plurality of spacers havebeen optionally selected and connected to each other, the triangle isformed; when four spacers have been selected and connected to eachother, the quadrangle is formed; and when six spacers have been selectedand connected, the hexagon is formed. However, upon determining thepitch, the closed figure thus formed is formed such that no spacer ispresent therein, and thus, for example, in the case where spacers areselected such that another spacer is present therein, they are excludedwhen determining the pitch.

In one example, the ratio (%) of the number of sides having the samelength among sides of a triangle, a quadrangle or a hexagon, which isthe closed figure thus formed (100×(number of sides of the samelength)/3 in the case of a triangle, 100×(number of sides of the samelength)/4 in the case of a hexagon, and 100×(number of sides of the samelength)/6 in the case of a hexagon) can be 85% or less. In anotherexample, the ratio may be 84% or less, 80% or less, 76% or less, 67% orless, 55% or less, or 40% or less. The lower limit of the ratio is notparticularly limited. That is, in some cases, since the lengths of allsides of the closed figure may not be the same, the lower limit of theratio may be 0%.

As described above, the arrangement of the spacers of the presentapplication is irregular in that at least a part thereof has differentpitches, but such irregularity is controlled under certain regularity.Here, the regularity may mean that the arrangement density of spacers issubstantially close to each other between certain regions.

For example, if the normal pitch of the plurality of irregularlyarranged spacers is P, when two or more square regions with 10 P as alength of one side have been optionally selected on the surface of thebase layer, the standard deviation of the number of spacers present ineach square region is 2 or less.

The term normal pitch means a distance between the centers of adjacentspacers in a state where the plurality of spacers, in actuality,irregularly disposed on the base layer are placed so that all of thespacers are virtually disposed at the same pitch in consideration of thenumber of the spacers and the area of the base layer.

The manner to confirm a virtual state where all of the above-mentionedspacers are disposed so as to have the same pitch is known, which can beachieved by using a random number generating program such as, forexample, CAD, MATLAB, STELLA or Excel.

In addition, the standard deviation is a numerical value representing adegree of scattering of the number of the spacers, which is a numericalvalue determined by a positive square root of dispersion.

That is, when at least two or more of the rectangular regions have beenoptionally designated on the surface of the base layer that spacers areformed thereon and then the standard deviation of the numbers of spacersexisting in the regions has been obtained, the standard deviation is 2or less. In another example, the standard deviation may be 1.5 or less,1 or less, or 0.5 or less. In addition, the standard deviation meansthat the lower the numerical value is, the desired regularity isachieved, and thus the lower limit is not particularly limited, whichmay be 0, for example.

Also, here, the number of the designated rectangular regions is notparticularly limited as long as it is 2 or more, but in one example, itmay be selected as the number that the rectangular regions areoptionally selected so as not to overlap each other on the surface ofthe base layer, provided that the area occupied by the optionallyselected regions is about 10% or more, 20% or more, 30% or more, 40% ormore, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or moreof the total area of the base layer.

Furthermore, the range of the normal pitch (P) forming one side of thearbitrary rectangular region can be determined by the number of spacerspresent on the base layer and the area of the relevant base layer, asdescribed above, which is not particularly limited, and usually, it maybe determined in a range of 100 μm to 1,000 μm.

Although not particularly limited, the average number of spacers presentin optionally selected square regions as above may be, for example,about 80 to 150 or so. In another example, the average number may be 82or more, 84 or more, 86 or more, 88 or more, 90 or more, 92 or more, 94or more, 96 or more, or 98 or more. Also, in another example, theaverage number may be 148 or less, 146 or less, 144 or less, 142 orless, 140 or less, 138 or less, 136 or less, 134 or less, 132 or less,130 or less, 128 or less, 126 or less, 124 or less, 122 or less, 120 orless, 118 or less, 116 or less, 114 or less, or 112 or less.

Also, the ratio (SD/A) of the average number (A) of the spacers and theabove-mentioned standard deviation (SD) may be 0.1 or less. In anotherexample, the ratio may be 0.09 or less, 0.08 or less, 0.07 or less, 0.06or less, 0.05 or less, 0.04 or less, or 0.03 or less.

The average number (A) or the ratio (SD/A) may be optionally changed,and for example, the numerical value may be changed in consideration ofthe transmittance, the cell gap and/or the uniformity of the cell gaprequired in the device to which the substrate is applied, and the like.

In another example, when the surface of the base layer on which theirregularly disposed spacers are formed has been divided into two ormore regions having the same area, the standard deviation of the numberof the spacers in each unit region may be 2 or less.

Here, the meaning of the standard deviation and the specific examplesthereof are as described above.

That is, in the example, when the base layer has been divided into atleast two regions having the same area and the standard deviation of thenumber of the spacers present in each divided unit region has beenobtained, the standard deviation thereof is 2 or less. In this case, theshape of each divided unit region is not particularly limited as long asthe relevant unit regions are divided so as to have the same area, butit may be, for example, a triangular, square, or hexagonal region. Inaddition, in another example, the standard deviation in the above statemay be 1.5 or less, 1 or less, or 0.5 or less, and the lower limitthereof is not particularly limited, as described above, which may be 0,for example.

Here, the number of unit regions is not particularly limited, but in oneexample, the base layer may be divided into two or more, four or more,six or more, eight or more, or ten or more regions having the same area.Here, since it means that the higher the number of the divided regions,the more uniform the density of the spacers is maintained, the upperlimit of the number of divided regions is not particularly limited.

When the virtual square region with P, which is a normal pitch, as oneside has been selected on the substrate on which the plurality ofspacers are disposed so as to have regularity and irregularitysimultaneously, the average number of spacers existing in the relevantregion may be in a range of 0 to 4. In another example, the averagenumber may be 3.5 or less, 3 or less, 2.5 or less, 2 or less, or 1.5 orless. Also, in another example, the average number may be 0.5 or more.Here, the number of square regions of which the length of one side isoptionally designated as the normal pitch (P) is not particularlylimited as long as it is two or more, but in one example, it may beselected as the number that the square regions are optionally selectedso as not to overlap each other on the surface of the base layer,provided that the area occupied by the optionally selected region isabout 10% or more, 20% or more, 30% or more, 40% or more, 50% or more,60% or more, 70% or more, 80% or more, or 90% or more of the total areaof the base layer.

The entire density of the plurality of spacers can be adjusted so thatthe ratio of the area occupied by the spacers is about 50% or lessrelative to the total area of the base layer. In another example, theratio may be about 45% or less, about 40% or less, about 35% or less,about 30% or less, about 25% or less, about 20% or less, about 15% orless, about 10% or less, about 9.5% or less, 9% or less, 8.5% or less,8% or less, 7.5% or less, 7% or less, 6.5% or less, 6% or less, 5.5% orless, 5% or less, 4.5% or less, 4% or less, 3.5% or less, 3% or less,2.5% or less, 2% or less, or 1.5% or less. In another example, the ratiomay be about 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more,0.5% or more, 0.6% or more, 0.7% or more, 0.8% or more, 0.9% or more, or0.95% or more.

When an optical device has been implemented by disposing a plurality ofspacers on the base layer in the above form, the uniform opticalcharacteristics can be ensured without causing the so-called moirephenomenon, while the spacers maintain the uniform pitch (cell gap)between the substrates.

The respective numerical values may be changed, if necessary, and forexample, the numerical values may be changed in consideration of thetransmittance, the cell gap and/or the uniformity of the cell gaprequired in the device to which the substrate is applied, and the like.

The plurality of spacers may be arranged such that their spacing normaldistribution diagram represents a predetermined shape.

Here, the spacing normal distribution diagram is a distribution diagramshowing the pitch between the spacers as the X-axis and the ratio of thespacers having the relevant pitch among all the spacers as the Y-axis,where the ratio of the spacers is a ratio obtained when the number ofthe entire spacer has been 1.

The pitch in the description related to the spacing normal distributiondiagram herein is a length of sides in a triangle, a quadrangle or ahexagon, which is the above-mentioned closed figure.

The distribution diagram can be obtained using a known random numbercoordinate program, for example, a CAD, MATLAB or STELLA random numbercoordinate program or the like.

In one example, the plurality of spacers may be disposed such that ahalf height area in the distribution diagram is in a range of 0.4 to0.95. In another example, the half height area may be 0.6 or more, 0.7or more, or 0.85 or more. Also, in another example, the half height areamay be 0.9 or less, 0.85 or less, 0.8 or less, 0.75 or less, 0.7 orless, 0.65 or less, 0.6 or less, 0.55 or less, or 0.5 or less.

The plurality of spacers may be arranged such that a ratio (FWHM/Pm) ofthe half height width (FWHM) to the average pitch (Pm) in thedistribution diagram is 1 or less. In another example, the ratio(FWHM/Pm) may be 0.05 or more, 0.1 or more, 0.11 or more, 0.12 or more,or 0.13 or more. Also, in another example, the ratio (FWHM/Pm) is about0.95 or less, about 0.9 or less, about 0.85 or less, about 0.8 or less,about 0.75 or less, about 0.7 or less, about 0.65 or less, about 0.6 orless, about 0.55 or less, about 0.5 or less, about 0.45 or less, orabout 0.4 or less.

When at least 80% or more, 85% or more, 90% or more, or 95% or more ofspacers have been selected to form a triangle, quadrangle or hexagon,which is the above-described closed figure, the above-mentioned averagepitch (Pm) is an average of the lengths of the respective sides of thetriangle, quadrangle or hexagon formed by the selected spacers. Here,the spacers are also selected so that the formed triangles, quadranglesor hexagons do not share vertexes with respect to each other.

The plurality of spacers may be disposed such that the half height width(FWHM) in the distribution diagram is in a range of 0.5 μm to 1,000 μm.In another example, the half height width (FWHM) may be about 1 μm ormore, 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm ormore, 7 μm or more, 8 μm or more, 9 μm or more, 10 μm or more, 11 μm ormore, 12 μm or more, 13 μm or more, 14 μm or more, 15 μm or more, 16 μmor more, 17 μm or more, 18 μm or more, 19 μm or more, 20 μm or more, 21μm or more, 22 μm or more, 23 μm or more, or 24 μm or more. In anotherexample, the half height width (FWHM) may be about 900 μm or less, 800μm or less, 700 μm or less, 600 μm or less, 500 μm or less, 400 μm orless, 300 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, 90μm or less, 80 μm or less, 70 μm or less, 60 μm or less, 50 μm or less,40 μm or less, or 30 μm or less.

The plurality of spacers may be disposed such that the maximum height(Fmax) of the spacing normal distribution diagram is 0.006 or more andless than 1. In another example, the maximum height (Fmax) may be about0.007 or more, about 0.008 or more, about 0.009 or more, or about 0.0095or more. Also, in another example, the maximum height (Fmax) may beabout 0.9 or less, about 0.8 or less, about 0.7 or less, about 0.6 orless, about 0.5 or less, about 0.4 or less, about 0.3 or less, about 0.2or less, about 0.1 or less, about 0.09 or less, about 0.08 or less,about 0.07 or less, about 0.06 or less, about 0.05 or less, about 0.04or less, about 0.03 or less, or about 0.02 or less.

When an optical device has been implemented by disposing a plurality ofspacers on to have the spacing normal distribution diagram in such aform, the uniform optical characteristics can be ensured without causingthe so-called moire phenomenon, while the spacers maintain the uniformpitch (cell gap) between the substrates.

The concept of degree of irregularity is introduced for a plurality ofspacers to be disposed so as to simultaneously have irregularity andregularity as above. Hereinafter, a method for designing the arrangementof the spacers having such a form will be described.

In order to achieve the arrangement of the spacers having theabove-mentioned regularity and irregularity simultaneously, a step ofstarting from a normal arrangement state and relocating the spacers tohave irregularity is performed.

Here, the normal arrangement state is a state where the plurality ofspacers are disposed on the base layer such that a regular triangle, asquare or a regular hexagon in which all sides have the same length canbe formed. FIG. 18 is a state in which spacers are disposed to form thesquare as an example. The length P of one side of the square in thisstate may be equal to the above-mentioned normal pitch. In such anarrangement state, a circle region having a radius of a lengthproportional to the length P of one side is designated on the basis of apoint where one spacer exists, and the program is set so that the onespacer can be randomly moved in the region. For example, FIG. 18schematically shows a form in which the circle region having the radiusof the length of 50% (0.5 P) relative to the length P is set and thespacer moves to any point in the region. The above-described arrangementcan be achieved by applying such a movement to spacers of at least 80%or more, 85% or more, 90% or more, 95% or more, or 100% (all spacers).

In such a design method, the ratio for the length P which becomes theradius of the circle region may be defined as a degree of irregularity.In one example, the degree of irregularity in the design manner may beabout 5% or more, about 10% or more, about 15% or more, about 20% ormore, about 25% or more, about 30% or more, about 35% or more, about 40%or more, about 45% or more, about 50% or more, about 55% or more, about60% or more, or about 65% or more. In one example, the degree ofirregularity may be about 95% or less, about 90% or less, about 85% orless, or about 80% or less.

The arrangement having the above-described irregularity and regularitysimultaneously can be achieved by designing the arrangement of thespacers in the same manner as above and forming the spacers according tothe designed arrangement.

Also, here, although the case where the normal state starts from thesquare has been exemplified, the normal state may be other figures suchas a regular triangle or a regular hexagon, and in this case, theabove-described arrangement can also be achieved.

Furthermore, the means for designing the arrangement of the spacers inthe same manner as above is not particularly limited, and a known randomnumber coordinate program such as, for example, a CAD, MATLAB, STELLA orExcel random number coordinate program can be used.

For example, after the arrangement of the spacers is first designed inthe same manner as above, a mask having a pattern according to therelevant design and the like may be manufactured, and such spacers maybe implemented by applying the relevant mask to the above-describedlithography or imprinting method, and the like.

The substrate can be produced through processes of light irradiationusing an imprinting mask containing a light-shielding layer, developmentof an uncured resin layer, and etching of a black layer, and the like.By applying such a method, it is possible to produce a substrate, havingexcellent adhesiveness, of a desired structure without adverse effectssuch as occurrence of foreign materials by a simple process.

FIG. 19 is a diagram schematically showing a process of producing such asubstrate. As in FIG. 19 , in a state of forming the black layer (2000)and the uncured resin layer (3001) to form spacers on the surface of thebase layer (1000), an imprinting mask containing a light-shielding layeris pressed thereon. The imprinting mask containing a light-shieldinglayer may have a form in which a light-shielding film (902) is patternedon the surface of the light-transmissive main body (901) as in FIG. 19 .Here, the pattern of the light-shielding film (902) is determineddepending on the pattern shape of the desired spacer. If necessary, thesurface of the main body (901) on which the pattern of thelight-shielding film (902) is formed may be subjected to appropriatemold releasing treatment.

In this state, the uncured resin layer (3001) on the light-shieldingmask is irradiated with light. By such irradiation, the resin layer(3001) in the portion where the light-shielding film (902) is not formedin the light-shielding mask is irradiated with light and cured, and theresin layer (3001) under the light-shielding film (902) is not cured. Inthe drawing, uncured parts are indicated by dots. Subsequently, theuncured resin layer is removed in an appropriate manner, and thisprocess is referred to as developing. Subsequently, after thedeveloping, the substrate having the above structure can be produced byremoving the black layer at the part where the resin layer has beenremoved by the developing.

The light-shielding masks that can be used in the above process vary,and one example thereof is shown in FIG. 20 . The mask of FIG. 20 has aform that a concave hemispherical shape (9011) is formed on one surfaceof a light-transmissive main body (for example, ultraviolet-transmissivemain body), and the light-shielding film (902) is formed on a portionwhere the hemispherical shape is not formed on the surface on which thehemispherical shape (9011) is formed. As shown in the drawing, thehemispherical shape (9011) may be produced by forming an imprinting mold(901) on one side of the main body (9) of the imprinting mask andforming the hemispherical shape (9011) and the light-shielding film(902) on the mold (901). If necessary, the surface of the mold (901) onwhich the light-shielding film (902) is formed may be subjected toappropriate mold releasing treatment. Here, the shape of the concaveportion (9011) is determined depending on the shape of the desiredspacer, which is not particularly limited. In an example of FIG. 20 ,the concave portion has a hemispherical shape.

FIG. 21 is an example of performing the process shown in FIG. 19 usingthe mask shown in FIG. 20 . A curable resin layer (200) such as anultraviolet curable type is first formed on the surface of the baselayer (100) and the mask (900) is pressed on the resin layer (200).Then, if the resin layer (200) is cured by irradiating the top of themask (900) with ultraviolet rays or the like, the resin layer is curedaccording to the shape of the concave portion (9011) formed on the mask(900), whereby a spacer may be formed and subsequently, theabove-described developing and etching processes may proceed.

When the pressing process is performed by applying the imprinting maskon which the concave portion (9011) or the like is formed as in FIGS. 19and 21 , the penetration of foreign materials such as oxygen into theresin layer, which is cured in the curing process, becomes difficult, sothat the curing can be performed more effectively.

Therefore, in one example, the imprinting mask containing alight-shielding layer may comprise a light-transmissive main body that aconcave portion is formed on one surface thereof and a light-shieldingfilm existing in a portion of the main body where the concave portion isnot formed.

The materials of the main body and the light-shielding film for formingsuch a mask and the production method thereof may follow a known manner.

Generally, in the production process of the optical device, an alignmentfilm is additionally formed on the spacer surface of the substrateformed in the same manner as above. There are various kinds of alignmentfilms, but for example, when a normal rubbing alignment film is formed,physical contact such as rubbing is applied to the substrate surfaceduring the formation process of the alignment film. If the stickingforce between the spacers and the black layer is not ensured properly inthis process, there is a problem that the spacers formed once are lostdue to the external force due to the physical contact. Therefore,additional processing is required to increase the sticking force betweenthe resin layer and the black layer, and generally, such a treatmentincludes a heat treatment process for applying appropriate heat to thesubstrate between the developing process and the etching process. As amethod for enhancing adhesive force between the resin layer and theblack layer without the heat treatment process, for example, a method ofincreasing a light quantity or the like in the ultraviolet rayirradiation process to enhance the degree of curing of the resin layermay be considered. However, the present inventors have confirmed thatthere is a problem that foreign materials remain on a substrate of aspacer pattern or the like in a method of simply enhancing only thedegree of curing.

However, the present applicant has confirmed that by controlling thelight quantity upon light irradiation together with the pressing speedof the mask in the above process, the high adhesive force between theblack layer and the resin layer can be ensured while preventingoccurrence of foreign materials even when the above-described heattreatment process is omitted, if necessary.

A production method of a substrate of the present application comprisesa process of pressing an imprinting mask containing a light-shieldinglayer on a resin layer of a laminate comprising a base layer; a blacklayer formed on the base layer and a light curable resin layer formed onthe black layer and simultaneously irradiating the resin layer on themask with light.

In the production method of the present invention, the pressing speed ofthe imprinting mask containing the light-shielding layer is controlledto 0.3 mpm (meters per minute) or more and the light quantity of theirradiated light is controlled to 300 mJ/cm² or more. Through thiscontrol, the object of the present application can be achieved.

Here, the pressing speed of the mask can be achieved by controlling thespeed at which the light-shielding mask is covered and pressed onto theresin layer in the continuous process of pressing the light-shieldingmask on the resin layer formed on the black layer and simultaneouslyirradiating it with light. For example, if the process is performed by aroll-to-roll method or a roll imprinting method, the pressing speed canbe controlled by controlling the movement speed of the resin layerand/or the rotation speed of the roll on which the mask is formed, andthe like. The present inventors have confirmed that the height of theresidual film of the resin layer increases as the pressing speedincreases and the elevated residual film facilitates the foreignmaterials that may be present on the base layer surface or the resinlayer to escape to the outside of the pressing region.

The pressing speed of the mask helps to remove foreign materials byincreasing the height of the residual film as the speed is higher, wherethe upper limit is not particularly limited. The speed may be, forexample, about 2 mpm or less, 1.5 mpm or less, 1 mpm or less, 0.8 mpm orless, 0.6 mpm or less, or 0.5 mpm or less or so, but is not limitedthereto.

The resin layer can be cured by irradiating the resin layer with lightthrough the mask while pressing the mask in the same manner as above. Atthis time, the wavelength of the light to be irradiated is determineddepending on the kind of the resin layer, which is not particularlylimited, and in general, ultraviolet rays in a wavelength range of about300 to 400 nm can be applied. At this time, the light quantity of theirradiated light can be adjusted to about 300 mJ/cm² or more. Such alight quantity range can be made in connection with the above-mentionedpressing speed, so that a spacer having excellent adhesiveness to a goodblack layer can be formed without foreign materials. In another example,the light quantity may be about 350 mJ/cm² or more, about 400 mJ/cm² ormore, about 450 mJ/cm² or more, about 500 mJ/cm² or more, about 550mJ/cm² or more, about 600 mJ/cm² or more, about 650 mJ/cm² or more, orabout 685 mJ/cm² or more or so. The larger the value of the lightquantity, the higher the adhesiveness can be secured, where the upperlimit is not particularly limited, but for example, it may be about2,000 mJ/cm² or less, about 1,500 mJ/cm² or less, about 1,000 mJ/cm² orless, about 800 mJ/cm² or less, or about 750 mJ/cm² or less or so.

The production method of the present application may further comprise aprocess of developing the resin layer following the above process andetching the black layer after developing the resin layer. In thedeveloping process of the resin layer, the irradiated light is shieldedby the light-shielding film of the light-shielding mask, whereby theuncured portion can be removed. The developing process can be performedby a known manner, and for example, the developing process can beperformed using a treating agent known to be capable of removing theuncured resin layer, where as the treating agent, a developer having anamine (NH₃) and a hydroxyl group (OH) is known. The developing processcan be performed through appropriate treatment using the developer asabove, and for example, the developing process can be performed byapplying the developer in a spray developing manner at a pressure ofabout 2 bar or more and in a temperature range of 20° C. to 50° C.

The black layer can be removed by the etching process following thedeveloping process. By this process, the black layer existing in theportion where the resin layer has been removed by the developing can beremoved. The etching process can be performed by a known manner, and forexample, it can be performed by treating the substrate with an etchantsuch as phosphoric acid, nitric acid, and acetic acid or an etchantmixed with two or more of the foregoing. The etching process may beperformed at a temperature range of about 40° C. to 50° C. for 30seconds to 30 minutes or so, but the specific processing conditions maybe changed.

As described above, according to the production method of the presentapplication, it is possible to produce a substrate having excellentcharacteristics without a separate step such as a heat treatment processfor improving adhesiveness between the resin layer (spacer) and theblack layer.

Accordingly, the production method of the present application may notperform the heat treatment process between the developing process andthe black layer etching process.

The manner in which the respective processes are performed is notparticularly limited and may be performed according to a known mannerother than performing the control of the pressing speed and the lightquantity.

In addition, the kinds and shapes of the base layer, the black layer,the spacer material, and the like applied in the above process are asdescribed above.

Furthermore, as the applied spacer material, for example, a mixture ofvarious acrylate compounds and an initiator may be used.

As the acrylate compound, one or a mixture of two or more of acrylatecompounds such as a monofunctional acrylate such as methyl(meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl(meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate,sec-butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl(meth)acrylate, 2-ethylbutyl (meth)acrylate, n-octyl (meth)acrylate,isobornyl (meth)acrylate, isooctyl (meth)acrylate, isononyl(meth)acrylate, lauryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate,hydroxyalkyl (meth)acrylate of 2-hydroxypropyl (meth)acrylate,4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate or8-hydroxyoctyl (meh)acrylate, and the like, or hydroxyalkylene glycol(meth)acrylate of 2-hydroxyethylene glycol (meth)acrylate or2-hydroxypropylene glycol (meth)acrylate, and the like and/or amultifunctional acrylate such as a bifunctional acrylate such as1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate,neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate,neopentylglycol adipate di(meth)acrylate, hydroxypivalic acid neopentylglycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactonemodified dicyclopentenyl di(meth)acrylate, ethylene oxide modifieddi(meth)acrylate, di(meth)acryloxyethyl isocyanurate, allylatedcyclohexyl di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate,dimethylol dicyclopentane di(meth)acrylate, ethyleneoxide modifiedhexahydrophthalic acid di(meth)acrylate, tricyclodecane dimethalol(meth)acrylate, neopentyl glycol modified trimethylpropanedi(meth)acrylate, adamantane di(meth)acrylate or9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene; a trifunctional acrylatesuch as trimethylolpropane tri(meth)acrylate, dipentaerythritoltri(meth)acrylate, propionic acid modified dipentaerythritoltri(meth)acrylate, pentaerythritol tri(meth)acrylate, propyleneoxidemodified trimethylolpropane tri(meth)acrylate, trifunctional urethane(meth)acrylate or tris(meth)acryloxyethyl isocyanurate; atetrafunctional acrylate such as diglycerin tetra(meth)acrylate orpentaerythritol tetra(meth)acrylate; a pentafunctional acrylate such aspropionic acid-modified dipentaerythritol penta(meth)acrylate; and ahexafunctional acrylate such as dipentaerythritol hexa(meth)acrylate,caprolactone modified dipentaerythritol hexa(meth)acrylate or a reactantof urethane (meth)acrylate (ex. isocyanate monomer) andtrimethylolpropane tri(meth)acrylate, urethane acylate, epoxy acrylate,polyester acrylate or polyether acrylate, may be used.

Such a substrate formed by the method of the present application can beapplied to various applications, where a representative application canbe exemplified by formation of an optical device.

An exemplary optical device of the present application may comprise thesubstrate and a second substrate disposed opposite to the substrate andmaintaining a gap with the substrate by the spacer in the substrate.

In the optical device, a light modulation layer may be present in a gapbetween two substrates. In the present application, the term lightmodulation layer may include all known types of layers capable ofchanging at least one characteristic among characteristics such aspolarization states, transmittance, color tones and reflectance ofincident light depending on purposes.

For example, the light modulation layer is a layer comprising a liquidcrystal material, which may be a liquid crystal layer switched between adiffusion mode and a transparent mode by on-off of a voltage, forexample, a vertical electric field or a horizontal electric field, aliquid crystal layer switched between a transparent mode and a blockingmode, a liquid crystal layer switched between a transparent mode and acolor mode, or a liquid crystal layer switched between color modes ofdifferent colors.

The light modulation layers capable of performing the actions as above,for example, liquid crystal layers, are variously known. As oneexemplary light modulation layer, a liquid crystal layer used in atypical liquid crystal display can be used. In another example, thelight modulation layer may also be various types of so-called guest hostliquid crystal layers, polymer dispersed liquid crystal layers,pixel-isolated liquid crystal layers, suspended particle devices orelectrochromic devices, and the like.

The polymer dispersed liquid crystal layer (PDLC) is a superordinateconcept including a PILC (pixel isolated liquid crystal), a PDLC(polymer dispersed liquid crystal), a PNLC (polymer network liquidcrystal) or a PSLC (polymer stabilized liquid crystal), and the like.The polymer dispersed liquid crystal layer (PDLC) may comprise, forexample, a liquid crystal region containing a polymer network and aliquid crystal compound dispersed in a state of being phase-separatedfrom the polymer network.

The implementation manner or form of the light modulation layer is notparticularly limited, and any known method may be employed without anylimitation depending on purposes.

In addition, the optical device may further comprise additional knownfunctional layers, such as a polarizing layer, a hard coating layerand/or an antireflection layer, if necessary.

Advantageous Effects

The present application provides a substrate and a method for producingthe same. The present application can provide, in a substrate having astructure including a base layer, a black layer and a spacer, which aresequentially formed, a substrate having excellent adhesiveness of thespacer to the base layer or the black layer and ensuring appropriatedarkening properties, and can also provide a production method capableof effectively producing such a substrate without adverse effects suchas occurrence of foreign materials without separate treatment such asheat treatment.

MODE FOR INVENTION

Hereinafter, the present application will be specifically described byway of examples, but the scope of the present application is not limitedby the following examples.

Example 1

A mask of the type as shown in FIG. 20 was produced and spacers wereproduced using the same. According to the form shown in FIG. 20 , themask was produced by forming concave portions (9011) on a PET(poly(ethylene terephthalate)) main body (9) through an imprinting mold(901), forming a light-shielding layer (AlOxNy) (902) on the surface onwhich no concave portion (9011) was formed and then forming a releaselayer on the light-shielding layer (902) and the concave portions(9011). At this time, the concave portion was formed into ahemispherical shape having a width in a range of approximately 24 μm to26 μm, and approximately 9 μm to 10 μm or so. In addition, the concaveportions were formed such that the arrangement of the spacers was suchthat the degree of irregularity according to an example described inFIG. 18 was about 70% or so.

A crystalline ITO (indium tin oxide) electrode layer was formed on a PC(polycarbonate) base layer, and a black layer was formed thereon.

The black layer was formed into a three-layer structure (AlON/Al/AlON)having the total thickness of about 200 nm or so by depositing aluminumoxynitride (AlON), aluminum (Al) and aluminum oxynitride (AlON) tothicknesses of about 60 nm, 80 nm and 60 nm or so, respectively. Here,aluminum is a metal whose physical ductility value is known to beapproximately 0.62 or so.

Subsequently, about 2 to 3 mL of a mixture (UV resin) of a conventionalultraviolet curable acrylate binder and an initiator used in productionof a column spacer was dropped on the black layer, and while the droppedmixture was pressed with the imprinting mask, ultraviolet rays wereirradiated to cure the UV resin layer. Here, as the binder, a binder ofacrylate series was used as a known binder for column spacers, where abinder obtained by mixing a monofunctional acrylate such as hydroxyethylacrylate, isobornyl acrylate, methyl methacrylate or cyclohexyl acrylateand a multifunctional acrylate such as HMDA (1,6-hexanediol diacrylate),TMPTA (trimethylolpropane triacrylate) or PETTA (pentaerythritoltetraacrylate), and the like with D-1173, D-TPO, Igacure 184 or the likeas an initiator in a weight ratio of 85-95:15-5 (acrylate compounds:initiator) was used.

Also, the above process was performed by a roll imprinting methodperformed in a state where the mask was mounted on a roll.

In the above process, the pressing speed of the mask was adjusted toabout 0.3 mpm or so and the ultraviolet irradiation was performed bybeing irradiated with ultraviolet rays having a wavelength range ofabout 300 to 400 nm at a light quantity of about 418 mJ/cm².

Thereafter, the uncured UV resin layer (200) was removed (developed)with a developer having an amine (NH₃) and a hydroxyl group (OH) and bya spray developing method under a condition of a pressure of about 2 barand a temperature of 30° C., and the black layer of the part, where theuncured UV resin layer was removed, was subjected to etching at atemperature of about 40° C. to 50° C. for about 1 minute or so using amixed etchant of phosphoric acid, nitric acid and acetic acid, andremoved (etched) to form spacers on the ITO electrode layer and theblack layer of the PC base layer.

FIGS. 22A-B illustrate top down and side views, respectively, ofscanning electron microscopy (SEM) images of a substrate and of thespacers arranged on the substrate produced by such a method and theirarrangement state (irregularity degree 70%).

The adhesiveness between the spacers produced as above and the blacklayer was evaluated by the following peel test. A pressure-sensitiveadhesive tape (Nichiban Tape, CT-24) (peel force: 3.72 to 4.16 N/10 mm,peel angle: 180 degrees, JIS Z 1522 standard) was formed on the surfaceof the substrate, on which the spacers were formed, with a rectangularattachment area of about 24 mm in width and about 40 mm in length. Atthe time of attachment, it was attached by applying a load of about 200g on the pressure-sensitive adhesive tape using a roller. Thereafter,the pressure-sensitive adhesive tape was peeled off in the longitudinaldirection using a tensile tester at a peeling speed of about 30 mm/s anda peel angle of 180 degrees. FIG. 23 is a view confirming whether or notthe spacers are lost after the peeling.

The disappearance of the pattern was further observed with an opticalmicroscope (Olympus BX 51) at a magnification of 50 times (eyepiece lens10 times×objective lens 5 times) and confirmed. Five arbitrary regionswere selected from the total attachment area (24 mm×40 mm) to determinethe disappearance, and the degree of loss of the pattern was calculatedvia the average value. The calculation of pattern attachment force wasevaluated by introducing the cross-cut method of ASTM D3359 and setting100× the number of non-lost spacer patterns/the number of the entirepattern before measuring attachment force as attachment force (patternretention rate), and as a result of evaluation, the attachment force wasin a level of more than about 85% (pattern loss rate: 15% or less). FIG.24 is the result of confirming whether or not foreign materials occur inthe above process, and it can be confirmed from FIG. 24 that the processcan proceed without occurrence of foreign materials. The pattern lossrate is a value obtained by subtracting the pattern retention rate from100.

Example 2

Spacers were manufactured in the same manner as in Example 1, providedthat the spacers were produced by setting the pressing speed to about0.4 mpm or so and adjusting the light quantity to about 685 mJ/cm² orso. FIG. 25 shows the result of confirming the foreign materialcharacteristics in the process of producing the spacer, FIG. 26 is theresult of confirming whether or not the patterns are lost in the samemanner as in Example 1, and FIG. 27 is an OM image after forming a knownalignment film on the produced substrate and performing rubbingtreatment thereon.

It can be confirmed from FIGS. 25 to 27 that according to the method ofthe present application, there is no foreign material during the processand a substrate having excellent adhesiveness of the spacer to the blacklayer is produced. In addition, the pattern retention rate of thesubstrate measured by the same peel test as in Example 1 was in a levelof more than about 85% (pattern loss rate: 15% or less).

Comparative Example 1

A spacer-containing substrate was produced in the same manner, exceptthat in the process of Example 1, the irradiation light quantity ofultraviolet rays was adjusted to about 240 mJ/cm².

FIG. 28 is the result of evaluating adhesiveness between the spacers andthe black layer for the substrate as above in the same manner as inExample 1, and it can be confirmed from the comparison of FIGS. 23 and28 that in the case of Comparative Example 1, the adhesiveness is notensured and thus the patterns are lost. The pattern retention rate ofthe substrate measured in the same manner as in Example 1 was in a levelof about 65% or less (pattern loss rate: more than 35%).

Comparative Example 2

A spacer-containing substrate was produced in the same manner, exceptthat in the process of Example 1, the irradiation light quantity ofultraviolet rays was adjusted to about 281 mJ/cm². FIG. 29 is the resultof evaluating adhesiveness between the spacers and the black layer forthe substrate as above in the same manner as in Example 1, and it can beconfirmed from the comparison of FIGS. 23 and 29 that in the case ofComparative Example 2, the adhesiveness is not ensured and thus thepatterns are lost. The pattern retention rate of the substrate measuredin the same manner as in Example 1 was in a level of about 65% or less(pattern loss rate: more than 35%).

Comparative Example 3

A spacer-containing substrate was prepared in the same manner as inComparative Example 2, except that the pressing speed of the mask wascontrolled to about 0.1 mpm or so. FIG. 30 is the result of evaluatingwhether or not foreign materials occur during the production process ofthe substrate as above, and it can be confirmed from the result that theforeign materials occur excessively. Such excessive foreign materialoccurrence was a level where the substrate could not be used.

Comparative Example 4

A spacer-containing substrate was prepared in the same manner as inComparative Example 2, except that the pressing speed of the mask wascontrolled to about 0.2 mpm or so. FIG. 31 is the result of evaluatingwhether or not foreign materials occur during the production process ofthe substrate as above, and it can be confirmed from the result that theforeign materials occur excessively. Such excessive foreign materialoccurrence was a level where the substrate could not be used.

The invention claimed is:
 1. A method for producing a substrate having abase layer, a black layer formed on the base layer and spacers formed onthe black layer, the method comprising: pressing an imprinting mask ontoa light curable resin layer disposed on the black layer to shape thelight curable resin layer into the shape of the spacers; and irradiatingthe light curable resin layer to cure a portion of the light curableresin layer being shaped into the spacers, wherein the imprinting maskincludes a light-shielding layer which shields remaining portions of thelight curable resin layer that are not being shaped into the spacers,wherein a pressing speed of the imprinting mask is 0.3 mpm or more, andwherein a light quantity provided during irradiation of the lightcurable resin layer is 300 mJ/cm² or more.
 2. The method for producing asubstrate according to claim 1, wherein the imprinting mask comprises: alight-transmissive main body, wherein a molded form of the spacers isrecessed into a surface of the main body, and wherein thelight-shielding layer is formed on a remaining surface of the main bodywhere the molded form is not present.
 3. The method for producing asubstrate according to claim 1, wherein the pressing of the imprintingmask is performed by a roll imprinting method.
 4. The method forproducing a substrate according to claim 1, further comprising:developing the resin layer after irradiation to remove uncured portionsof the resin layer that were shielded by the light-shielding layerduring irradiation; and etching the black layer exposed by removal ofthe uncured portions of the resin layer.
 5. The method for producing asubstrate according to claim 4, wherein a heat treatment process is notperformed between developing the resin layer and etching the blacklayer.
 6. The method for producing a substrate according to claim 1,wherein the substrate further comprises an electrode layer disposedbetween the black layer and the base layer and wherein the black layeris in contact with the electrode layer.
 7. The method for producing asubstrate according to claim 6, wherein the black layer is a multilayerstructure comprising a first layer and at least one second layer,wherein the first layer is a metal layer and the at least one secondlayer is one of a metal oxide layer, a metal nitride layer, or a metaloxynitride layer, and wherein each of the metals in the metal layer, themetal oxide layer, the metal nitride layer, and the metal oxynitridelayer has a physical ductility value of 0.55 or more.
 8. The method forproducing a substrate according to claim 1, wherein the base layer is aflexible base layer.
 9. The method for producing a substrate accordingto claim 1, wherein a ratio (T/B) of an area (B) of the black layer andan area (T) of a bottom of the spacer is in a range of 0.5 to 1.5. 10.The method for producing a substrate according to claim 7, wherein theblack layer is a multilayer structure comprising the first layer and twosecond layers, and wherein each second layer is disposed on opposingsides of the first layer.
 11. The method for producing a substrateaccording to claim 1, wherein the spacers have a hemispherical portionon the ends of the spacers opposite the black layer.